I don't think you should get rid of the head or really do anything that ~Samuel-Havana said at all. This is your style and design method and you should stick with that. Changing all of that would completely change the effect of this image, which is near perfect, in my opinion. The only things I can really think of is the hands. It's a bit difficult to distinguish its left hand from its flank, and it's hard to tell where it's gripping the weapon from. Other than that, I'm in love with everything. Your work is beautiful, and I want models of all of it in my room.
I only say this because it seems like the turret/sensors on the chest seem like they could do a good enough job on their own, making a head slightly redundant. But in war machines, redundancy is a good thing! Though I also wonder how much of the head's vision would be obscured by the chest? I dunno, I'm being silly and trying to reason with a painting of a giant fighting mech, ha ha.
I love your work by the way, this piece included! I am a huge fan! You manage to bring these fantastic future weapons systems into imagery that makes them very believable!
Maybe look into changing the feet and leg design to be more realistic in supporting the mech, I.E; bigger foot surface, tracked feet. Legs more aligned with the torso, more practical locomotive and positional shapes. maybe cover up the mid section remove the frontal turet cone, add grenade launchers along the shoulders.
Thats pretty much what I can think of for tweaking.
A really great piece you made here but for some reason the feet of the mech are bothering me. To me, the feet are too small to stabilize it and looks like it would tip over. But then again, its an art concept and you can do what you will, but I am just stating my thoughts.